<?php

namespace think\db\builder;

use think\db\Builder;

/**
 * Pgsql数据库驱动
 */
class Pgsql extends Builder
{

  /**
   * limit分析
   * @access protected
   * @param mixed $limit
   * @return string
   */
  public function parseLimit($limit)
  {
    $limitStr = '';
    if (!empty($limit)) {
      $limit = explode(',', $limit);
      if (count($limit) > 1) {
        $limitStr .= ' LIMIT ' . $limit[1] . ' OFFSET ' . $limit[0] . ' ';
      } else {
        $limitStr .= ' LIMIT ' . $limit[0] . ' ';
      }
    }
    return $limitStr;
  }

  /**
   * 字段和表名处理
   * @access protected
   * @param string $key
   * @param array  $options
   * @return string
   */
  protected function parseKey($key, $options = [])
  {
    $key = trim($key);
    if (strpos($key, '$.') && false === strpos($key, '(')) {
      // JSON字段支持
      list($field, $name) = explode('$.', $key);
      $key                = $field . '->>\'' . $name . '\'';
    } elseif (strpos($key, '.')) {
      list($table, $key) = explode('.', $key, 2);
      if (isset($options['alias'][$table])) {
        $table = $options['alias'][$table];
      }
    }
    if (isset($table)) {
      $key = $table . '.' . $key;
    }
    return $key;
  }

  /**
   * 随机排序
   * @access protected
   * @return string
   */
  protected function parseRand()
  {
    return 'RANDOM()';
  }
}
